JPH11158514A - Method for joining metallic bulk material and joined body of metallic bulk material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for joining metallic bulks reducing clearance on the joined boundary of metallic bulk materials, making the joining condition better and capable of suppressing the deformation of the metallic bulk materials at the time of joining. SOLUTION: This method is the one in which a plurality metallic bulk materials 1 are joined by using a discharge plasma sintering method. Roughening working to the joined faces 2 of the metallic bulk materials 1 is executed only by machining. Suitable clearance can be given to the space between the joined faces 2, a plasma discharge phenomenon is made easy to occur to promote the inside exothermic effect, and furthermore, the effect of the entanglement of the ruggedness in the joined faces 2 can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining metal bulk materials by a discharge plasma sintering apparatus, and a joined body having good joining conditions between metal bulk materials joined by this method.

[0002]

2. Description of the Related Art Conventionally, a plurality of metal bulk materials have been joined using a discharge plasma sintering apparatus. At this time, in order to roughen the joining surface of each metal bulk material, After a cutting process is performed on the joint surface, a roughening process is performed by performing a finishing process by grinding.

[0003]

However, if the joining surface is cut and then finished by grinding as described above, the roughness of the joining surface becomes too fine, and the joining of the metal bulk material is performed. There has been a problem that voids (air layers) are formed at various parts of the interface to generate gaps. Further, when the joining temperature is increased to prevent the generation of the gap, there is a problem that the metal bulk material is greatly deformed.

[0004] The present invention has been made in view of the above points, and has a small gap at a joining interface of a metal bulk material, a good joining state, and can suppress deformation of the metal bulk material at the time of joining. It is an object of the present invention to provide a joining method. Another object of the present invention is to provide a joined body of a metal bulk material having a small gap at a joining interface of the metal bulk material.

[0005]

According to a first aspect of the present invention, there is provided a method for joining a plurality of metal bulk materials using a discharge plasma sintering method. It is characterized in that the surface roughening of the joint surface 2 is performed only by cutting. Claim 2 of the present invention
The method for bonding a metal bulk material described in (1) is characterized in that, in addition to the configuration of the first aspect, a powdery metal inclusion 3 is provided at the bonding interface.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the metal inclusion 3 has a function of reducing an oxide film on the surface of the metal bulk material 1. It is characterized by being an activating material. The joined body of metal bulk materials according to claim 4 of the present invention is a joined body of metal bulk materials formed by joining a plurality of metal bulk materials 1 using a discharge plasma sintering method. It is characterized in that the surface 2 is roughened by using the metal bulk material 1 which has been cut only.

According to a fifth aspect of the present invention, there is provided a joined body made of a metal bulk material, wherein a powdery metal inclusion 3 is provided at a joining interface in addition to the structure of the fourth aspect. It is. According to a sixth aspect of the present invention, there is provided a joined body of a metal bulk material having an action of reducing an oxide film on the surface of the metal bulk material 1 as the metal inclusion 3 in addition to the structure of the fifth aspect. Is characterized by using the following.

[0008]

Embodiments of the present invention will be described below. In the present invention, as shown in FIG.
The surface 2 is subjected to only a cutting process to perform a roughening process.
The roughness of the bonding surface 2 ranges from 3 μm to 0.1 μm in maximum roughness (Rmax).
Preferably, it is set to about 3 mm. If the maximum roughness of the joining surface 2 is less than 3 μm or more than 0.3 mm, a plasma discharge phenomenon is unlikely to occur between the joining surfaces 2 of the opposed metal bulk materials 1, and the joining may not be performed well. There is. Thereafter, each metal bulk material 1 is set in a discharge plasma sintering apparatus so that the bonding surfaces 2 face each other, and a voltage such as a high-frequency pulse voltage is applied to the metal bulk material 1 so that the plasma is applied between the bonding surfaces 2. By causing the discharge phenomenon, the metal bulk material 1 is thermally welded to form a joined body.

As described above, by performing the roughening process only on the joining surface 2 of the metal bulk material 1 by cutting, the joining surface 2
Between them, a plasma discharge phenomenon easily occurs, the internal heat generation effect can be promoted, and the unevenness of the bonding surface 2 can be entangled. In this case, there are few gaps, and the joining state can be improved satisfactorily. Further, since the bonding can be performed at a relatively low temperature, the deformation of the metal bulk material 1 can be suppressed to a minimum. Further, since the finishing process by grinding is unnecessary, the processing time of the joining surface 2 of the metal bulk material 1 can be shortened.

FIG. 2 shows another embodiment. In this method, a powdery metal inclusion 3 is provided between joining surfaces 2 of opposed metal bulk materials 1. Other configurations are the same as those of the above embodiment. This metal inclusion 3
Has an average particle size of about 0.1 μm to 0.3 mm,
The material is preferably the same as the metal bulk material 1,
Any material having a lower melting point than the metal bulk material 1 may be used. Further, the metal inclusion 3 can be provided between the joining surfaces 2 so that the thickness becomes 1 mm or less.

In the above-mentioned conventional method, no inclusion is provided between the joining surfaces 2 of the metal bulk material 1. However, in the present invention, since the metal inclusion 3 is provided between the joining surfaces 2, A discharge plasma phenomenon can be generated between the particles of the inclusions 3, and the plasma discharge phenomenon is easily generated, and the internal heat generation effect can be promoted. The condition can be improved satisfactorily. In addition, since discharge occurs at a lower temperature than that of the metal bulk material 1, bonding can be performed at a relatively low temperature, and deformation of the metal bulk material 1 can be suppressed to a minimum.

The metal inclusion 3 is preferably an activating material having an action of reducing an oxide film (metal oxide film) on the surface of the metal bulk material 1, for example, metal carbide or metal hydrogen. Can be used. By using the activating material having the function of reducing the oxide film on the surface of the metal bulk material 1 as described above, the metal bulk material 1
Can reduce oxides by chemically acting on the oxide film covering the surface of the metal bulk material 1 and the bonding surface 2 of the metal bulk material 1.
Are easily activated and the bonding is facilitated, and the bonding can be promoted. In particular, it has a great effect on bonding of the metal bulk material 1 of aluminum or titanium whose surface is easily oxidized.

[0013]

The present invention will be described below in detail with reference to examples. (Example 1) Bonding surface 2 of metal bulk material 1 of beryllium copper
The surface was roughened only by cutting. The maximum roughness of the bonding surface 2 was set to 25 μm (by analysis with a laser microscope). In addition, the cutting process was performed by rotating the metal bulk material 1 with a blade applied to the joining surface 2. This was joined by a discharge plasma sintering device to form a joined body. The conditions for spark plasma sintering were a temperature of 800 to 900 ° C. and a pressure of about 160 kg / cm ² .

(Embodiment 2) The maximum roughness of the bonding surface 2 is 50 μm.
Except having set it to m, it carried out similarly to Example 1, and formed the joined body. (Comparative Example) Except that the joining surface 2 was cut and then ground to set the maximum roughness of the joining surface 2 to 1 μm.
A joined body was formed in the same manner as in Example 1. The grinding was performed by applying a grindstone to the bonding surface 2 while rotating the metal bulk material 1.

Observation of the bonding interfaces of Examples 1 and 2 and the comparative example revealed that the larger the roughness of the bonding surface 2 was, the smaller the gap at the bonding interface was, and the better the bonding was. Table 1 shows the results
Shown in In the column of joining degree in Table 1, ◎ indicates that there is no gap at the joining interface, ○ indicates that there is almost no gap, and X indicates that there is a gap. Further, in Examples 1 and 2, it was found that a discharge plasma phenomenon occurs at a temperature lower than that of the comparative example by about 200 ° C., and it is possible to perform the bonding at a lower temperature by performing the surface roughening processing only by the cutting processing. It can be seen that the deformation of the metal bulk material 1 can be suppressed. The same effect can be obtained not only with beryllium copper but also with a metal bulk material 1 of another material. Also, the smaller the rigidity of the material of the metal bulk material 1 is, the better the bonding is performed even if the roughness of the bonding surface 2 is increased.

[0016]

[Table 1]

Example 3 The same roughening process as in Example 1 was performed on the bonding surface 2 (bottom surface) of a cylindrical metal bulk material 1 of stainless steel (SUS). Next, two metal bulk materials 1
Stainless steel (SU) as metal inclusion 3 between joining surfaces 2 of
The powder of S) (with an average particle diameter of 10 μm to 0.3 mm) was inserted at a thickness of 1 mm, and this was joined with a discharge plasma sintering apparatus in the same manner as in Example 1 to form a joined body. The metal inclusions 3 were selected from those having the above average particle diameter using a laser diffraction method or a sieve.

Observation of the bonding interface of Example 3 revealed that the bonding interface was small and had good bonding. Normally, the sintering temperature is 9 with only the stainless metal bulk material 1.
Good bonding cannot be achieved unless the temperature is raised to 00 ° C. or higher. However, by inserting the powder of the metal inclusion 3 between the bonding surfaces 2 as in Example 3, good bonding could be achieved at a temperature lower than that. . In the third embodiment, the metal inclusions 3 of the same type of iron-based material as the metal bulk material 1 were used. Similar effects can be obtained by using powder as the metal inclusion 3. Similar effects can be obtained not only with stainless steel but also with a metal bulk material 1 of another material.

Example 4 The same roughening process as in Example 1 was performed on the joining surface 2 (bottom surface) of a cylindrical metal bulk material 1 made of titanium. Next, a powder of titanium carbide or titanium hydride having a thickness of 1 mm was inserted as a metal inclusion 3 between the joining surfaces 2 of the two metal bulk materials 1, and this was subjected to discharge plasma sintering in the same manner as in Example 1. The joined body was formed by joining with an apparatus.

Observation of the bonding interface of Example 4 showed that the bonding interface was small and had good bonding. Normally, the surface of the titanium metal bulk material 1 is covered with a titanium oxide film and is a material that is difficult to be activated and is difficult to join. I was able to. In addition, other easily oxidizable materials (aluminum and copper) as well as titanium
The same effect can be obtained even with the metal bulk material 1 described above.

[0021]

As described above, according to the first aspect of the present invention, when a plurality of metal bulk materials are bonded by using a discharge plasma sintering method, a roughening process of a bonding surface of the metal bulk materials is performed. Is performed only by cutting, so that an appropriate gap can be provided between the joining surfaces, the plasma discharge phenomenon easily occurs, the internal heating effect can be promoted, and the effect of the entanglement of the unevenness of the joining surface Since there is little gap at the joining interface of the metal bulk material, the joining state can be improved satisfactorily, and since the joining can be performed at a relatively low temperature, deformation of the metal bulk material can be minimized. You can do it.

According to the second aspect of the present invention, since a powdery metal inclusion is provided at the bonding interface, a discharge plasma phenomenon can be generated between particles of the metal inclusion, and the plasma can be generated. Discharge phenomena are likely to occur and the internal heat generation effect can be promoted, and there are few gaps at the bonding interface of the metal bulk material, and the bonding state can be improved well, and at a lower temperature than the metal bulk material. Since discharge occurs, bonding at a relatively low temperature is possible, and deformation of the metal bulk material can be further suppressed.

According to the third aspect of the present invention, since the metal inclusion is an activating material having an action of reducing an oxide film on the surface of the metal bulk material, the metal inclusion is used as an activating material for the metal inclusion. By reducing the joining surface of the bulk material, it is easy to activate and join easily, and the joining can be promoted. According to a fourth aspect of the present invention, there is provided a joined body of metal bulk materials formed by joining a plurality of metal bulk materials by using a discharge plasma sintering method, wherein the joining surface is roughened. Since a metal bulk material processed only by cutting is used, an appropriate gap can be provided between bonding surfaces, a plasma discharge phenomenon easily occurs, and an internal heating effect can be promoted and bonding can be performed. Due to the effect of the entanglement of the surface irregularities, a gap is reduced at the bonding interface of the metal bulk material.

According to the fifth aspect of the present invention, since a powdery metal inclusion is provided at the bonding interface, a discharge plasma phenomenon can be generated between particles of the metal inclusion. The plasma discharge phenomenon easily occurs, the internal heat generation effect can be promoted, and the gap at the joining interface of the metal bulk material is reduced. The invention according to claim 6 of the present invention uses an activating material having an action of reducing an oxide film on the surface of a metal bulk material as a metal inclusion,
By reducing the joining surface of the metal bulk material with the activation material of the metal inclusion, it becomes easy to activate and join easily,
This promotes bonding and reduces gaps at the bonding interface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the same.

[Explanation of symbols]

 1 Metal bulk material 2 Joining surface 3 Metal inclusion

Claims (6)

[Claims] 1. A method for joining a plurality of metal bulk materials by using a spark plasma sintering method, wherein the surface of the metal bulk materials is roughened only by cutting. Method. 2. The method for joining metal bulk materials according to claim 1, wherein a powdery metal inclusion is provided at the joining interface. 3. The method according to claim 2, wherein the metal inclusion is an activating material having an action of reducing an oxide film on the surface of the metal bulk material. 4. A joined body of metal bulk materials formed by joining a plurality of metal bulk materials using a spark plasma sintering method, wherein a roughening process of a joining surface is performed only by a cutting process. A joined body of a metal bulk material, wherein the joined body is formed by using a metal bulk material obtained by the above method. 5. The joined body of metal bulk materials according to claim 4, wherein a powdery metal inclusion is provided at the joining interface. 6. The joined body of metal bulk materials according to claim 5, wherein an activation material having an action of reducing an oxide film on the surface of the metal bulk material is used as the metal inclusion.